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Researchers assembled the first high-quality genome of Coelioxoides waltheriae, a Neotropical cleptoparasitic bee that lays its eggs in the nests of Tetrapedia diversipes. The genome is compact at 194.8 Mbp, with low repeat content rather than gene loss explaining its small size. Comparative genomic analysis across 42 hymenopteran species revealed that cleptoparasitism is associated with a strong bias toward gene family contractions, particularly in sensory perception, detoxification, and metabolic functions, while expansions were found in cuticle-related genes and transposable elements potentially involved in host infiltration.
Why it matters
Understanding the genomic basis of cleptoparasitism in bees may illuminate broader principles of how parasitic lifestyles evolve at the molecular level, with implications for studying host-parasite dynamics and pollinator ecology. Given that roughly 13% of bee species are cleptoparasites, this genomic reference provides a foundation for future conservation and ecological research on bee communities.
⚠️ Preprint – Noch nicht peer-reviewed
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Cleptoparasitism, or brood parasitism, is a striking behavioral strategy observed in approximately 13% of all bee species, yet its genomic underpinnings remain largely unexplored. We present the first high-quality genome assembly of the Neotropical cleptoparasitic bee Coelioxoides waltheriae (Nomadinae), a species that parasitizes the nests of Tetrapedia diversipes. The final assembly comprises 194.8 Mbp across 388 contigs, with an N50 of 1.47 Mbp and 97.4% BUSCO completeness, representing the second smallest genome among cleptoparasitic bees. Repetitive elements constitute only 14.6% of the genome, suggesting that its compact size is primarily driven by repeat reduction rather than gene loss. Comparative genomic analyses across 42 hymenopteran species revealed a pronounced contraction bias in gene family size changes in C. waltheriae (expansion ratio of 13.66%), a pattern also observed in other cleptoparasitic lineages. Expanded orthogroups presented functions associated with cuticle-related genes, transposases (e.g., PiggyBac ) potentially linked to host infiltration and defense, while contracted orthogroups showed significant reductions in sensory perception (e.g., odorant receptors), detoxification (e.g., cytochrome P450), and metabolic genes, reflecting the reduced ecological demands of a parasitic lifestyle. Furthermore, non-target DNA analysis identified associations with Roubikia mites (a known symbiont of its host), as well as fungi and bacteria, providing ecological context for this species. Our findings establish an important genomic reference for cleptoparasitic bees, demonstrating that the evolution of parasitism is associated with targeted gene family contractions alongside expansions, offering new insights into the genomic signatures of behavioral specialization.